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Warm-Up Earth’s Climate History

Lesson Question

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WK2 Words to Know

Fill in this table as you work through the lesson. You may also use the glossary to help you.

the transfer of energy through space

a time in the past when large parts of the Earth’s surface were covered with ice

a dark area on the surface of the Sun that is cooler than surrounding areas

a slowly moving, large body of ice and snow

a sudden eruption of energy from a small area of the Sun’s surface

shaped like a flattened circle 

a trace of an ancient organism preserved within a layer of rock

Lesson Goals

Explain how scientists study ancient climates.

Identify factors that can cause long-term change.

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Warm-Up Earth’s Climate History

Pangaea

Earth was once a massive called Pangaea, surrounded by

a single .

• Broke apart as the result of activity

• Affected Earth’s climate

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Earth’s Climate HistoryInstruction

Studying Ancient Climates

• Through careful research, scientists have discovered that climate change is a

and process.

• Scientists use clues that remain in natural elements to study and reconstruct past climate conditions. These include:

• pollen grains.

• tree rings.

• .

By studying clues from the past and comparing them to organisms today, scientists can draw specific conclusions about past climates.

Pollen Records

Flowering plants produce pollen grains.

• Pollen grains are well preserved in the layers in bodies of water.

• Scientists can analyze these pollen and make inferences

about the of the area.

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Tree Rings

Scientists can study tree rings to learn more about past .

• Trees generally produce one ring per year.

• Climate conditions influence tree .

• Patterns in the width of tree-rings, their , and their

composition reflect variations in the local climate

Different climates affect the width of the tree rings.

• In cool and dry climates, trees grow slowly, producing rings.

• In warm and wet climates, trees grow faster, producing rings.

Ice Ages

Over millions of years, Earth’s climate has gradually changed.

• Warm periods have alternated with periods, called ice ages.

• During ice ages, cover large parts of Earth’s surface.

• Glaciers shape the surface by transporting materials as they move and

carving away the beneath them.

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Earth’s Climate HistoryInstruction

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Ice Ages and Ancient Climates

Ice is one of the best preservers of the remains of life.

• Glacial deposits contain rocks, some of which contain fossils of different

and .

• Evidence from fossils has helped scientists identify several major ice ages.

• Scientists can also find clues by deep into the ice to collect ice cores.

Earth’s Position

The tilt of Earth’s axis and the of its orbit around the Sun change over time.

• Earth’s orbit is one of the causes of long-lasting

climate change.

• The of Earth’s axis is responsible for the seasons.

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Earth’s Climate HistoryInstruction

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Solar Energy

About every years, the Sun goes through a period during which it

emits more than normal.

• Solar

•

Volcanic Activity

Volcanic eruptions release gas and ash into the air.

• These materials reflect solar energy back into space and lowertemperatures.

Some volcanic eruptions expel greenhouse gases into the atmosphere.

• gases cause temperatures to rise.

Movement of Continents

When Pangaea broke apart, the movement of the continents caused changes in:

• wind patterns.

• currents.

• across Earth.

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Summary Earth’s Climate History

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Answer

Review: Key Concepts

Scientists study ancient climates by observing natural records.

Tree RingsPollan Grains Fossils

• With

records, scientists identify plants and infer what the climate was like in the area during a particular time period.

• Patterns in

rings reveal what conditions were like many years ago.

• Evidence from

helps

scientists identify major ice ages and other factors.

Lesson Question What factors can cause long-term climate change?

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Summary Earth’s Climate History

Review: Key Concepts

The causes of long-term climate change are many.

Earth’s Position

• Earth’s tilt and its

around the Sun change over time and cause climate change.

Solar Energy

• More sunspots can

Earth’s temperature.

Volcanic Activity

• Volcanic eruptions can cause both global warming and global

.

TectonicActivity

• The movement of continents changes wind and ocean currents, which affect

.

Use this space to write any questions or thoughts about this lesson.

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